Chapter 7: Proteins

Question 1

describe the structure of a protein

Answer 1

Folded amino acid chains

Question 2

describe the structure of an amino acid

Answer 2

Amino acids have 3 main groups

• Nitrogen containing amine group
• Carboxylic acid
• Side chain (Rx)

Question 3

How many different amino acids are there?

Answer 3

21

Question 4

Describe the primary protein structure

Answer 4

Amino acids bind together through peptide bonds to form a polypeptide (releases a water molecule)
Not yet a protein (must fold into next level of structure)

Question 5

Describe the secondary protein structure

Answer 5

Hydrogen bonds between non-adjacent amino acids lead to the formation of alpha helices and beta-pleated sheets

Question 6

Describe the tertiary protein structure

Answer 6

Interactions between amino acids side chains lead to further folding of the polypeptide chain; May result in a functional protein

Question 7

Describe the quaternary protein structure

Answer 7

Several proteins in their tertiary structure bind to form a final protein; each one is called a protein subunit

Question 8

How many amino acids are essential?

Answer 8

9

Question 9

define: transamination

Answer 9

Process of making non-essential amino acids by modifying other amino acids

Question 10

Define: conditionally essential amino acids

Answer 10

Conditionally essential amino acids: non-essential amino acids that become essential when the body cannot synthesize enough of them

Question 11

Define: complete proteins and the sources

Answer 11

Complete proteins: foods that have all nine essential amino acids
- All animal sources and soy, quinoa, and buckwheat

Question 12

Define: incomplete proteins and the sources

Answer 12

Incomplete proteins: foods missing 1 or more essential amino acids

• Plant sources
• The missing amino acids are called the limiting amino acid(s)
• Lysine is usually the limiting amino acid

Question 13

What do animal sources of protein also have in terms of nutritional value?

Answer 13

• Have B vitamins, iron, zinc, calcium

- Lower in fiber, higher in saturated fat and cholesterol ( which increases risk of heart disease)

Question 14

What do plant sources of protein also have in terms of nutritional value?

Answer 14

• Contain some B vitamins, iron, zinc, calcium

- Higher in fiber, unsaturated fats, and phytochemicals

Question 15

What is the idea behind complementing proteins?

Answer 15

• Consuming a variety of foods to get all your amino acids

Question 16

Define: amino acid pool

Answer 16

where we take amino acids from to compose a protein

Question 17

Define: denatured protein

Answer 17

Denatured protein: lacks 3d structure and loses function

Question 18

How does a denatured protein occur

Answer 18

Acids, heat, agitation all denature proteins

Question 19

Describe protein digestion in the mouth

Answer 19

mechanical digestion: chewing

Question 20

Describe protein digestion in the stomach

Answer 20

hydrochloric acid and pepsin begin the chemical digestion of protein; Proteins must be denatured and broken down into individual amino acids to be absorbed into the SI by active transport

Question 21

Describe protein digestion in the small intestine

Answer 21

protease secreted from the pancreas into the small intestine and the enzymes from the microvilli break down polypeptides into amino acids, dipeptides, and tripeptides; transport proteins move the products of protein digestion into the mucosal cell. Similar amino acids use the same transporter; if there is an overabundance of one, it may block the absorption of another. dipeptides and tripeptides enter the mucosal cells and are then broken down into single amino acids. amino acids pass into the blood next and travel to the liver which regulates the distribution of amino acids to the rest of the body

Question 22

What functions do proteins have (7)?

Answer 22

• body structure
• transport
• enzymes
• movement
• fluid balance
• protection from disease
• energy

Question 23

What is the main structural protein?

Answer 23

Collagen: main structural protein; most abundant; very stiff and strong
tendon

Question 24

What is elastin?

Answer 24

Elastin: another key structural protein that allows for elasticity; not as strong as collagen; makes up skin

Question 25

Explain this protein function: transport (3)

Answer 25

- Protein tracks in cells allow substances to “walk” in the tracks and permit transport around the cell - Hemoglobin transports oxygen around the body - Protein channels and pumps regulate movement of ions and molecules into and out of the cell

Question 26

Explain this protein function: movement

Answer 26

- Myosin and actin are proteins found in muscle | - Myosin proteins attach to actin proteins and kink their heads which causes muscle contraction and produces movemen

Question 27

Explain this protein function: fluid balance

Answer 27

- Water is attracted to positive and negative charges of amino acids found in blood proteins - This draws water into blood and out of extracellular space - If blood proteins are low, fluid can build up in the extracellular space leading to edema

Question 28

Explain this protein function: protection from disease

Answer 28

- Collagen in skin helps to restrict what can enter the body - If infectious agents enter, proteins called antibodies stick to these agents and promote their removal limiting the harm they cause

Question 29

How much energy comes from 1 gram of protein

Answer 29

4kcal

Question 30

define: marasmus

Answer 30

Marasmus: energy and protein deficiency; aka wasting syndrome; promotes: anemia, dehydration, heart irregularities, body temperature dysregulation

Question 31

define: kwashiorkor

Answer 31

Kwashiorkor: protein deficient but energy sufficient; distended, swollen abdomen but a slim appearance

Question 32

How can protein promote a caloric deficit (3)?

Answer 32

- Promoting fullness - Contributing to carbohydrate and lipid metabolism - Requires more energy to digest and absorb it (thermic effect)

Question 33

Fill in the blank: protein muscle synthesis increases ___ hours following weight training

Answer 33

24 hours

Question 34

How many grams of essential amino acids in the first 2 hours following exercise encourages muscle growth?

Answer 34

10g

Question 35

How much protein should athletes eat?

Answer 35

ACSM recommends increasing intake from 0.8g/kg to 1.2-2.0g/kg depending on intensity and load of training

Question 36

Fill in the blank: In the bone, _____ forms a matrix that calcium hardens

Answer 36

collagen

Question 37

How do proteins affect kidney health?

Answer 37

High protein diets tax the kidneys because they have more waste products to excrete

Question 38

What are 3 ways we can assess protein quality

Answer 38

- Protein digestibility corrected amino acid score (PDCAAS) - Digestible indispensable amino acid score (DIAAS) - Protein efficiency ratio (PER)

Question 39

Describe: Protein digestibility corrected amino acid score (PDCAAS)

Answer 39

- Compares amino acid content of food against standard amino acid profile (score from 0-1) - Takes into account digestibility of protein - Old industry standard but moving away from it; based on mice (checks feces to see if any left in the stool)

Question 40

Describe: Digestible indispensable amino acid score (DIAAS)

Answer 40

- Measures how well amino acids are digested in the ileum and more closely estimates the amount of amino acids absorbed by the body - Database still being built

Question 41

Describe: Protein efficiency ratio (PER)

Answer 41

- How much weight an animal gains when consuming a specific amount of protein, divided by the amount of food it consumed - Used in Canada

Question 42

Fill in the blank: _______ have more total protein and ______ than processed meats

Answer 42

Game meets; tryptophan

Question 43

Fill in the blank: Excessive supplementation (__________) does not promote further gains

Answer 43

>1.62g/kg body weight

Question 44

Define: Branched-chain amino acids (BCAA)

Answer 44

- Essential amino acids that have branched side chain - Are 35-40% of dietary essential amino acids found in body protein - Reduce muscle damage associated with weight training

Question 45

What are the health benefits of a vegetarian diet (3)

Answer 45

- High in fibre and phytochemicals and low in saturated fats - Vegetarians are more likely to have lower BMIs, total cholesterol, and LDL - At lower risk for heart disease, cancer, and CVD mortality

Question 46

What are the health risks of a vegetarian diet (3)

Answer 46

- Lower in vitamin D, omega-3 fatty acids, calcium, iron and zinc - Vitamin B12 is only found in animal products - Supplementation is recommended if these aren't sufficient in diet

Question 47

explain nitrogen levels and measuring proteins

Answer 47

- measuring nitrogen intake in the diet and output in urine can assess when someone is in a state of negative nitrogen balance, positive nitrogen balance (usually pregnancy), or at equilibrium